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Thread: PX1 Power plug was with reversed 12V Polarity. What to replace?

  1. #11
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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    Oops - my bad.

    Vdd generally means the Drain supply on CMOS circuits (positive power).
    Vss generally means the Source supply on CMOS circuits (ground common).
    Jimboha
    Springville, Utah

  2. #12
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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    I just measure the PIC at pins 1 and 14.... 0V =(

  3. #13
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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    Hi, it looks like as a minimum U3 the voltage regulator has been damaged.

    I would disconnect the 12V power and pixels and remove the board from its enclosure.

    Remove U3 from the board. The pins are quite close together and you can warm all three at the same time by sliding the soldering iron forwards and backwards whilst ery gently pulling on the part with long nose pliers or tweezers.

    Clean up the area around U3 and look for solder bridges.

    It should now be safe to power the board from a 5V source with the ‘Pixel Volt’ jumper in the 5V position. If that is the only damage the LEDs should function as expected.

    Let us know how you get on – if you’re really stuck and need the pixels there is a way to run using 5V until you can get a replacement part.


    http://doityourselfchristmas.com/wik...d-px1_RevE.PNG

    https://www.doityourselfchristmas.co...e=File:PX1.jpg

  4. #14
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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    Since the voltage regulator is dead, I would just cut the pins near the body of the device and unsolder one pin at a time, gently pulling on the cut pin with pliers. Trying to remove the pins at the same time will give you heartburn.

    2017 adding 2 more candy canes, 7 Mid trees and a Halloween show. Removing most 2812 strips and replacing them with bullet pixel mounting strips. Replacing many buck converter waterproof bags with printed boxes.

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  6. #15
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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    Quote Originally Posted by MartinMueller2003 View Post
    Since the voltage regulator is dead, I would just cut the pins near the body of the device and unsolder one pin at a time, gently pulling on the cut pin with pliers. Trying to remove the pins at the same time will give you heartburn.
    Yep, this is the best (and easiest) way.
    That's a feature not a bug.
    There's no charge for that.

  7. #16
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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    I doubt I have enough room to get something down there to cut. I'll try though. Maybe if I'm fast enough with a de-solder sucker.
    Can I still run my 12V pixel bulbs directly and connect 5V Power to the PX1 without the Voltage Regulator?

  8. #17
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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    Usually, but it depends on how the voltage regulator failed. Does it show open between the three leads, or are any leads connected to another, with 0 ohms??? If 0, you have to remove it or at lest cut the leads off. Once it is no longer 'present', you can bring in (regulated!) 5V via the ICSP header. The ICSP header pin #3 (3rd from left, while viewing from above with PIC dimple to the left) connects directly to V+ ping 14 of the PIC. The 2nd pin on the ICSP is ground, connects directly to pin 1 of the PIC.

    Make sure "Pixel Volt" jumper is on 12V.

    But you should also carefully inspect the traces on the PCB just in case you burned out some/one of them.

    Jimboha
    Springville, Utah

  9. #18
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    Default Re: PX1 Power plug was with reversed 12V Polarity. What to replace?

    The data line is always 5V (even on a 12v pixel string). I rarely us V+ from my controllers so there is no issue using just ground and data.

    2017 adding 2 more candy canes, 7 Mid trees and a Halloween show. Removing most 2812 strips and replacing them with bullet pixel mounting strips. Replacing many buck converter waterproof bags with printed boxes.

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